The present invention relates to waveguides, or more particularly to a connector assembly for the precision interconnection of mating arrays of parallel optical waveguides. The optical waveguides are preferably photolithographically formed on substrates.
It is known in the art to photolithographically produce optical waveguides on a substrate. Such optical waveguides connect optical information processing devices or connect such devices and other optical communication links such as glass optical fibers. Waveguides may also be used to create passive optical devices such as splitters, combiners, couplers, routers and the like. In commonly used applications, waveguides are densely packed on substrates and extremely small dimensions are generally required. The transverse dimension of such waveguides typically range from about 5 .mu.m to about 100 .mu.m, while the space between guides can be as little as 3 .mu.m. It is known in the art to produce waveguides with UV photopatterned polymeric materials. In this regard, see U.S. Pat. No. 4,609,252 which is incorporated herein by reference. It is often necessary to make an optical interconnection between waveguides having approximately rectangular cross-section and other waveguides, devices and/or optical fibers. These interconnections require a precision alignment at the interface between the devices. This is difficult to achieve when the device structures have different geometries. Moreover, no matter how well made, such interconnects result in loss of optical power. A further complication is that the alignment, once accomplished, is difficult to maintain under conditions of high vibration. It is therefore generally desired to minimize the number of interconnects, to facilitate the precision alignment at any necessary interconnects and to ensure the maintenance of alignment over time.
The present invention provides a raised rib structure which allows the precision alignment of a waveguide array with another corresponding waveguide array or light transmitting device having a raised rib configuration or fiber array. Such a raised rib structure serves as an optical interconnect between light transmitting devices. The device may be a printed waveguide structure which, when fabricated on a flexible substrate may include a flexible ribbon-type interconnect which can be run directly to a connector or to another device. The device itself may be laminated to a rigid structure such as a sheet of rigid plastic or glass with the flexible ribbon interconnects allowed to extend beyond the substrate and which can be fed to an optical connector or other interface between devices.
U.S. Pat. No. 4,111,522 discloses the alignment of glass fibers in a fiber-to-fiber connector. The foregoing does not suggest the aligned attachment of photolithographically formed waveguides on substrates nor a de-mateable connector for the interfacing of standing rib waveguide to conventional glass or polymer fiber. U.S. Pat. No. 5,375,184 shows a waveguide alignment device wherein a single waveguide is aligned with another single waveguide by means of mating guides. U.S. Pat. No. 5,024,505 shows a splicer for several individual strands of circular cross-section optical fibers.
It would be desirable to provide a means of connecting two or more ribbons of densely packed, small diameter, substantially parallel, photolithographically formed waveguides, especially rectangular cross-section waveguides on substrates. It has now been found that a good optical connection between waveguides can be achieved by mating the ends of waveguides to be connected in the base portion of a coupler having precision grooves. The ends of the waveguides are self-aligned by abutting them against the walls of the grooves. Once aligned, a cover plate maintains them in place.